Ice cube-making machines generally comprise an evaporator, a water supply and a refrigerant/warm gas circuit that includes a condenser and a compressor. The evaporator is connected to the water supply and to a circuit that includes the condenser and the compressor. Valves and other controls control the evaporator to operate cyclically in a freeze mode and a harvest mode. During the freeze mode, the water supply provides water to the evaporator and the circuit supplies refrigerant to the evaporator to cool the water and form ice cubes. During the harvest mode, the circuit converts the refrigerant to warm gas that is supplied to the evaporator, thereby warming the evaporator and causing the ice cubes to loosen and fall from the evaporator into an ice bin or hopper.
When installed in a location, such as a restaurant, where a small footprint is needed, ice making machines have been separated into two separate packages or assemblies. One of the packages contains the evaporator and the ice bin and is located within the restaurant. The other package contains the compressor and condenser, which are rather noisy. This package is located remotely from the evaporator, for example, outside the restaurant on the roof. The evaporator package is relatively quiet as the condenser and compressor are remotely located.
This two package ice cube-making machine has some drawbacks. It is limited to a maximum height distance of about 35 feet between the two packages because of refrigerant circuit routing constraints. Additionally, the compressor/condenser package weighs in excess of about 250 pounds and requires a crane for installation. Furthermore, service calls require the mechanic to inspect and repair the compressor/condenser package in the open elements, since it is typically located on the roof of a building. Due to inclement weather, it would be highly desirable to be able to work on the compressor in doors, since it is only the condenser that requires venting to the atmosphere.
During harvest mode, the condenser is bypassed so that refrigerant is supplied from the compressor in vapor phase to the evaporator. When the compressor is located a distance from the evaporator, the refrigerant tends to partially change to liquid phase as it traverses the distance, thereby affecting the efficiency warming or defrosting the evaporator. One prior art solution to this problem uses a heater to heat the vapor supply line. Another prior art solution locates a receiver in the same package as the evaporator and uses the vapor ullage of the receiver to supply vapor to the evaporator. Both of these solutions increase the size of the package and, hence, its footprint in a commercial establishment.
Thus, there is a need for a quiet ice cube-making machine that has a larger height distance between the evaporator and the condenser and a lighter weight for installation without the need for a crane.
There is also a need for an efficient way of providing vapor to an evaporator during harvest mode.